ORDERS OF MAMMALIA. 301 



psalterium opens by a wide aperture into the fourth and last 

 stomach, known as the " abomasumP This is a cavity of 

 considerable size, which secretes the true digestive fluid (gas- 

 tric juice), and it is here that the food is really digested. The 

 abomasum terminates, of course, in the commencement of the 

 small intestine. 



The Muminantia include a number of families, of which it 

 is only possible to notice the leading characters of the more 

 important ones — namely, the CameKdce, Gervidce, Giraffes, 

 and Gavicornia. 



The family CamelidoB comprises the Camel and Dromedary 

 of the Old World and the Llamas of the New, and is charac- 

 terized by having no horns, by having two incisors in the 

 upper jaw, and a pair of canines in both jaws ; while the foot 

 consists of only two toes, covered with imperfect nail-like 

 hoofs, and destitute of the two supplementary toes. The soles 

 of the feet are covered with a callous horny integument upon 

 which the animal walks. In the Camels the toes are conjoined 

 below by a callous pad, and the back is furnished with one or 

 two fleshy humps. The Arabian Camel or Dromedary has but 

 one hump, and its structure admirably adapts it for a beast of 

 burden in the sandy deserts of Arabia and Africa. One special 

 provision toward this end is the possession of large cells in 

 the paunch, in which a large quantity of water can be stored 

 up, thus enabling the animal to travel for days without drink- 

 ing. The Bactrian Camel resembles the Dromedary in most 

 respects, but it possesses two humps. The place of the Camels 

 of the Old World is filled in South America by the Llamas and 

 Alpacas (Auohenia), which have separate toes, and have no 

 hump. The Llama is extensively used as a beast of burden, 

 but the Alpaca is chiefly of value for its long wool, which is 

 largely manufactured. 



The family Gervidce includes the true Deer, and is charac- 

 terized by the fact that the forehead carries two soUd bony 

 antlers, which are not hollow, and are usually much branched. 

 With the single exception of the Reindeer, these appendages 

 are exclusively confined to the males, and they are deciduous; 

 that is to say, they are only produced at certain seasons (an- 

 nually, at the breeding-season), and, when they have fulfilled 

 their purpose, they are shed. They increase in size and in 

 the number of branches "every time they are reproduced, till in 

 the old males they may attain an enormous size. Among the 

 more familiar of the Deer may be mentioned the Elk, or Moose 

 (Aloes j^msrioanus) of Scandinavia and North America, the 



